1. Field of the Invention
The present invention relates to a printer capable of recording on both surfaces of a recording medium.
2. Description of the Related Art
One conventional printer receives a recording instruction for an image from an external apparatus, deconstructs into colors of cyan (C), magenta (M), and yellow (Y), pixels forming the image, and executes a recording operation of superimposing the colors as images onto each other. According to a technique for such printer, displacement of the recording positions of the image forming colors is prevented by holding the recording medium using a pair of rollers that include a grip roller that has protrusions thereon that protrude toward an outer periphery and a pinch roller that faces the grip roller, sandwiching the recording medium therebetween such that displacement of the recording positions of the colors forming images is prevented (see, e.g., Japanese Laid-Open Patent Publication No. 2000-15886).
In a case where a recording operation for both surfaces is executed using the printer, when the recording medium is held using the grip roller and the pinch roller sandwiched therebetween, marks of the protrusions of the grip roller are left on a recording surface on the front or the back surface of the recording medium on which duplex printing is executed. For a printer that executes a recording operation under a so-called sublimation transfer scheme in which a sublimation dye (sublimation pigment) included in an ink layer of an ink ribbon is transferred onto a recording layer of a recording medium to be recorded on, when the protrusion marks are left, the sublimation dye (sublimation pigment) can not be transferred well and therefore, the recording quality is degraded.
According to a conventional technique that is a countermeasure against the above and for a printer that thermally transfers an overcoat layer onto a recording surface having an ink thermally transferred thereon, the pressing force between a grip roller and a pinch roller is adjusted such that the grip roller is strongly pressed onto the recording surface before the transfer of the overcoat layer and is not strongly pressed onto the recording surface after the transfer (see, e.g., Japanese Laid-Open Patent Publication No. 2011-46157).
According to another conventional technique for a printer that thermally transfers an overcoat layer onto a recording surface having an ink thermally transferred thereon, when the overcoat layer is thermally transferred, the recording medium is conveyed by a feed roller having a smooth surface and thereby, contact of the protrusions of the grip roller with the recording surface having the overcoat layer thermally transferred thereon is prevented (see, e.g., Japanese Laid-Open Patent Publication No. 2011-46156).
According to a conventional technique for a printer that includes a printing head that executes a recording operation for a first surface of a recording medium and another printing head executing a recording operation for the back surface thereof, any contact of the grip roller with the recording surface is prevented by causing the distance in a path line between the printing head disposed on the same side as that of the grip roller against the recording medium, and the grip roller to be longer than a printing length of the recording medium (see, e.g., Japanese Laid-Open Patent Publication No. 2011-46155).
According to another conventional technique, a range is pressed and heated that corresponds to the protrusions of the grip roller in at least a printed area of a recording medium; a receptive layer disposed on the recording medium within the range is softened and pressed; and thereby, the protrusion marks are smoothed (see, e.g., Japanese Laid-Open Patent Publication No. 2008-207447).
However, according to the conventional techniques described in Japanese Laid-Open Patent Publication Nos. 2011-46157 and 2011-46156, although the protrusion marks tend to be inconspicuous, the protrusion marks remain in a recording area that abuts the protrusions of the grip roller and therefore, a problem arises in that a difference is generated in the recording quality depending on the recording position on the recording surface.
According to the conventional technique described in Japanese Laid-Open Patent Publication No. 2011-46155, the path length to convey the recording medium is increased and therefore, a problem arises in that the size of the printer is increased. According to the conventional technique described in Japanese Laid-Open Patent Publication No. 2008-207447, the mechanism to press and heat the recording medium is disposed and therefore, a problem arises in that the structure of the printer is complicated and the size thereof is increased.